1. Field of the Invention
The present invention relates generally to toner transfer belts used in electrophotographic (EP) printers, also called “intermediate transfer belts”, and more particularly to such a belt having a textured surface for enhanced toner transfer and to a method of forming the textured surface of the transfer belt.
2. Description of the Related Art
Single pass or multi-pass electrophotographic (EP) printers use single or multi layer intermediate transfer belts with very glossy, hard surfaces and pose toner transfer problems over the life of a customer replaceable unit (CRU) or a field replaceable unit (FRU) that adversely impact both print quality and CRU or FRU longevity.
Toner adheres to a photoconductive (PC) drum after the latent image development. The toner is held onto the PC by forces such as image forces (Coulomb forces), Van der Waals, and dispersion forces. These mechanical and electrical forces are relatively weak and without further plastic deformation or other large forces applied to the toner, the toner can be easily removed electrically or mechanically. Besides the mechanical forces applied to the toner, an electric field is present at the transfer nip which encourages the charged toner to transfer from the PC drum (toner bearing member) to the belt (toner receiving member).
As a result of the smooth and rigid nature of a typical transfer belt, the contact of the belt with isolated toner areas and the PC drum results in the creation of very high and localized pressures. Due to these highly localized pressures, the small toner features subsequently take on a large amount of pressure due to the very small and focused area of contact. Before the toner exits the transfer nip, it is believed that under the high, localized force, the toner particles adhere increasingly to one another as well as to the PC drum (“pressure fusing”). When the belt begins to separate from the PC drum at the exit of the transfer nip, regions of the compressed toner clumps remain adhered to the PC drum and do not transfer, despite the presence of the electric field and the other mechanical forces. These compressed toner clumps frequently produce print artifacts, such as voiding and in particular an example of bad voiding performance is illustrated in FIG. 3B. An example of good voiding performance is illustrated in FIG. 3A.
In order to compensate for these first transfer artifacts, a possible solution is to cover the outer functional surface of the transfer belt with a pure or mostly pure fluoropolymer. However, this can be expensive and its implementation as the solution would only be considered as a last resort. Thus, there is still a need for an innovation that solves the problem of first transfer print artifacts such as voiding of the transfer belt over the life of the belt in a more practical and cost effective manner.